The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Corneal Topography Reading Center (CTRC) provides data collection, quality control, storage, database generation and data analysis of corneal topography acquired during the CLEK Study. Corneal topography measurements are an ever increasingly important tool for the detection, diagnosis and long term management of keratoconus. Characterizing the longitudinal changes in corneal curvature is a major CLEK Study outcome variable. This proposal provides documentation and the rationale for establishing the CTRC to incorporate this valuable data set into the overall CLEK analysis picture. The CLEK Study elected, at the outset, to collect corneal topography data on all CLEK Study subjects, and elected not to establish or budget for a reading center or a set of specific aims to analyze these data due to concerns about the accuracy, precision, and interpretation of the curvature data produced. This proposal addresses each of these areas and provides the rationale for analyzing the growing data set. This proposal seeks support for a period of five years to provide for salaries, equipment, computer programming support, consultants, supplies and travel.